#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>
int main()
{
	int i = 0,x,y=0;
	while (scanf("%d", &y))
	{
		for (x = 1; x <= y; x++)
		{
			i = 2 * y + 1;
		}
		printf("%d\n", i);
	}
	return 0;
}